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annotate src/elab_err.sml @ 1303:c7b9a33c26c8

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Hopeful fix for the Great Unification Bug
author Adam Chlipala <adam@chlipala.net>
date Sun, 10 Oct 2010 14:41:03 -0400
parents 26197c957ad6
children 3a845f2ce9e9
rev   line source
adam@1303 1 (* Copyright (c) 2008-2010, Adam Chlipala
adamc@329 2 * All rights reserved.
adamc@329 3 *
adamc@329 4 * Redistribution and use in source and binary forms, with or without
adamc@329 5 * modification, are permitted provided that the following conditions are met:
adamc@329 6 *
adamc@329 7 * - Redistributions of source code must retain the above copyright notice,
adamc@329 8 * this list of conditions and the following disclaimer.
adamc@329 9 * - Redistributions in binary form must reproduce the above copyright notice,
adamc@329 10 * this list of conditions and the following disclaimer in the documentation
adamc@329 11 * and/or other materials provided with the distribution.
adamc@329 12 * - The names of contributors may not be used to endorse or promote products
adamc@329 13 * derived from this software without specific prior written permission.
adamc@329 14 *
adamc@329 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
adamc@329 16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
adamc@329 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
adamc@329 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
adamc@329 19 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
adamc@329 20 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
adamc@329 21 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
adamc@329 22 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
adamc@329 23 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
adamc@329 24 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
adamc@329 25 * POSSIBILITY OF SUCH DAMAGE.
adamc@329 26 *)
adamc@329 27
adamc@329 28 structure ElabErr :> ELAB_ERR = struct
adamc@329 29
adamc@329 30 structure L = Source
adamc@329 31 open Elab
adamc@329 32
adamc@329 33 structure E = ElabEnv
adamc@329 34 structure U = ElabUtil
adamc@329 35
adamc@329 36 open Print
adamc@329 37 structure P = ElabPrint
adamc@329 38
adamc@623 39 val simplCon = U.Con.mapB {kind = fn _ => fn k => k,
adamc@329 40 con = fn env => fn c =>
adamc@329 41 let
adamc@329 42 val c = (c, ErrorMsg.dummySpan)
adamc@628 43 val c' = ElabOps.hnormCon env c
adamc@329 44 in
adamc@329 45 (*prefaces "simpl" [("c", P.p_con env c),
adamc@329 46 ("c'", P.p_con env c')];*)
adamc@329 47 #1 c'
adamc@329 48 end,
adamc@623 49 bind = fn (env, U.Con.RelC (x, k)) => E.pushCRel env x k
adamc@792 50 | (env, U.Con.NamedC (x, n, k, co)) => E.pushCNamedAs env x n k co
adamc@623 51 | (env, _) => env}
adamc@329 52
adamc@329 53 val p_kind = P.p_kind
adamc@623 54
adamc@623 55 datatype kind_error =
adamc@623 56 UnboundKind of ErrorMsg.span * string
adamc@623 57
adamc@623 58 fun kindError env err =
adamc@623 59 case err of
adamc@623 60 UnboundKind (loc, s) =>
adamc@623 61 ErrorMsg.errorAt loc ("Unbound kind variable " ^ s)
adamc@329 62
adamc@329 63 datatype kunify_error =
adamc@329 64 KOccursCheckFailed of kind * kind
adamc@329 65 | KIncompatible of kind * kind
adamc@329 66
adamc@623 67 fun kunifyError env err =
adamc@329 68 case err of
adamc@329 69 KOccursCheckFailed (k1, k2) =>
adamc@329 70 eprefaces "Kind occurs check failed"
adamc@623 71 [("Kind 1", p_kind env k1),
adamc@623 72 ("Kind 2", p_kind env k2)]
adamc@329 73 | KIncompatible (k1, k2) =>
adamc@329 74 eprefaces "Incompatible kinds"
adamc@623 75 [("Kind 1", p_kind env k1),
adamc@623 76 ("Kind 2", p_kind env k2)]
adamc@329 77
adamc@329 78
adamc@329 79 fun p_con env c = P.p_con env (simplCon env c)
adamc@329 80
adamc@329 81 datatype con_error =
adamc@329 82 UnboundCon of ErrorMsg.span * string
adamc@329 83 | UnboundDatatype of ErrorMsg.span * string
adamc@329 84 | UnboundStrInCon of ErrorMsg.span * string
adamc@329 85 | WrongKind of con * kind * kind * kunify_error
adamc@329 86 | DuplicateField of ErrorMsg.span * string
adamc@329 87 | ProjBounds of con * int
adamc@329 88 | ProjMismatch of con * kind
adamc@329 89
adamc@329 90 fun conError env err =
adamc@329 91 case err of
adamc@329 92 UnboundCon (loc, s) =>
adamc@329 93 ErrorMsg.errorAt loc ("Unbound constructor variable " ^ s)
adamc@329 94 | UnboundDatatype (loc, s) =>
adamc@329 95 ErrorMsg.errorAt loc ("Unbound datatype " ^ s)
adamc@329 96 | UnboundStrInCon (loc, s) =>
adamc@329 97 ErrorMsg.errorAt loc ("Unbound structure " ^ s)
adamc@329 98 | WrongKind (c, k1, k2, kerr) =>
adamc@329 99 (ErrorMsg.errorAt (#2 c) "Wrong kind";
adamc@329 100 eprefaces' [("Constructor", p_con env c),
adamc@623 101 ("Have kind", p_kind env k1),
adamc@623 102 ("Need kind", p_kind env k2)];
adamc@623 103 kunifyError env kerr)
adamc@329 104 | DuplicateField (loc, s) =>
adamc@329 105 ErrorMsg.errorAt loc ("Duplicate record field " ^ s)
adamc@329 106 | ProjBounds (c, n) =>
adamc@329 107 (ErrorMsg.errorAt (#2 c) "Out of bounds constructor projection";
adamc@329 108 eprefaces' [("Constructor", p_con env c),
adamc@329 109 ("Index", Print.PD.string (Int.toString n))])
adamc@329 110 | ProjMismatch (c, k) =>
adamc@329 111 (ErrorMsg.errorAt (#2 c) "Projection from non-tuple constructor";
adamc@329 112 eprefaces' [("Constructor", p_con env c),
adamc@623 113 ("Kind", p_kind env k)])
adamc@329 114
adamc@329 115 datatype cunify_error =
adamc@329 116 CKind of kind * kind * kunify_error
adamc@329 117 | COccursCheckFailed of con * con
adamc@329 118 | CIncompatible of con * con
adamc@329 119 | CExplicitness of con * con
adamc@413 120 | CKindof of kind * con * string
adamc@1071 121 | CRecordFailure of con * con * (con * con * con) option
adam@1303 122 | TooLifty of ErrorMsg.span * ErrorMsg.span
adam@1303 123 | TooUnify of con * con
adamc@329 124
adamc@329 125 fun cunifyError env err =
adamc@329 126 case err of
adamc@329 127 CKind (k1, k2, kerr) =>
adamc@329 128 (eprefaces "Kind unification failure"
adamc@623 129 [("Kind 1", p_kind env k1),
adamc@623 130 ("Kind 2", p_kind env k2)];
adamc@623 131 kunifyError env kerr)
adamc@329 132 | COccursCheckFailed (c1, c2) =>
adamc@329 133 eprefaces "Constructor occurs check failed"
adamc@329 134 [("Con 1", p_con env c1),
adamc@329 135 ("Con 2", p_con env c2)]
adamc@329 136 | CIncompatible (c1, c2) =>
adamc@329 137 eprefaces "Incompatible constructors"
adamc@329 138 [("Con 1", p_con env c1),
adamc@329 139 ("Con 2", p_con env c2)]
adamc@329 140 | CExplicitness (c1, c2) =>
adamc@329 141 eprefaces "Differing constructor function explicitness"
adamc@329 142 [("Con 1", p_con env c1),
adamc@329 143 ("Con 2", p_con env c2)]
adamc@413 144 | CKindof (k, c, expected) =>
adamc@413 145 eprefaces ("Unexpected kind for kindof calculation (expecting " ^ expected ^ ")")
adamc@623 146 [("Kind", p_kind env k),
adamc@329 147 ("Con", p_con env c)]
adamc@1071 148 | CRecordFailure (c1, c2, fo) =>
adamc@329 149 eprefaces "Can't unify record constructors"
adamc@1071 150 (("Summary 1", p_con env c1)
adamc@1071 151 :: ("Summary 2", p_con env c2)
adamc@1071 152 :: (case fo of
adamc@1071 153 NONE => []
adamc@1071 154 | SOME (nm, t1, t2) =>
adamc@1071 155 [("Field", p_con env nm),
adamc@1071 156 ("Value 1", p_con env t1),
adamc@1071 157 ("Value 2", p_con env t2)]))
adam@1303 158 | TooLifty (loc1, loc2) =>
adam@1303 159 (ErrorMsg.errorAt loc1 "Can't unify two unification variables that both have suspended liftings";
adam@1303 160 eprefaces' [("Other location", Print.PD.string (ErrorMsg.spanToString loc2))])
adam@1303 161 | TooUnify (c1, c2) =>
adam@1303 162 (ErrorMsg.errorAt (#2 c1) "Substitution in constructor is blocked by a too-deep unification variable";
adam@1303 163 eprefaces' [("Replacement", p_con env c1),
adam@1303 164 ("Body", p_con env c2)])
adamc@329 165
adamc@329 166 datatype exp_error =
adamc@329 167 UnboundExp of ErrorMsg.span * string
adamc@329 168 | UnboundStrInExp of ErrorMsg.span * string
adamc@329 169 | Unify of exp * con * con * cunify_error
adamc@339 170 | Unif of string * ErrorMsg.span * con
adamc@329 171 | WrongForm of string * exp * con
adamc@329 172 | IncompatibleCons of con * con
adamc@329 173 | DuplicatePatternVariable of ErrorMsg.span * string
adamc@329 174 | PatUnify of pat * con * con * cunify_error
adamc@329 175 | UnboundConstructor of ErrorMsg.span * string list * string
adamc@329 176 | PatHasArg of ErrorMsg.span
adamc@329 177 | PatHasNoArg of ErrorMsg.span
adamc@819 178 | Inexhaustive of ErrorMsg.span * pat
adamc@329 179 | DuplicatePatField of ErrorMsg.span * string
adamc@329 180 | Unresolvable of ErrorMsg.span * con
adamc@329 181 | OutOfContext of ErrorMsg.span * (exp * con) option
adamc@329 182 | IllegalRec of string * exp
adamc@329 183
adamc@329 184 val p_exp = P.p_exp
adamc@329 185 val p_pat = P.p_pat
adamc@329 186
adamc@329 187 fun expError env err =
adamc@329 188 case err of
adamc@329 189 UnboundExp (loc, s) =>
adamc@329 190 ErrorMsg.errorAt loc ("Unbound expression variable " ^ s)
adamc@329 191 | UnboundStrInExp (loc, s) =>
adamc@329 192 ErrorMsg.errorAt loc ("Unbound structure " ^ s)
adamc@329 193 | Unify (e, c1, c2, uerr) =>
adamc@329 194 (ErrorMsg.errorAt (#2 e) "Unification failure";
adamc@329 195 eprefaces' [("Expression", p_exp env e),
adamc@329 196 ("Have con", p_con env c1),
adamc@329 197 ("Need con", p_con env c2)];
adamc@329 198 cunifyError env uerr)
adamc@339 199 | Unif (action, loc, c) =>
adamc@339 200 (ErrorMsg.errorAt loc ("Unification variable blocks " ^ action);
adamc@329 201 eprefaces' [("Con", p_con env c)])
adamc@329 202 | WrongForm (variety, e, t) =>
adamc@329 203 (ErrorMsg.errorAt (#2 e) ("Expression is not a " ^ variety);
adamc@329 204 eprefaces' [("Expression", p_exp env e),
adamc@329 205 ("Type", p_con env t)])
adamc@329 206 | IncompatibleCons (c1, c2) =>
adamc@329 207 (ErrorMsg.errorAt (#2 c1) "Incompatible constructors";
adamc@329 208 eprefaces' [("Con 1", p_con env c1),
adamc@329 209 ("Con 2", p_con env c2)])
adamc@329 210 | DuplicatePatternVariable (loc, s) =>
adamc@329 211 ErrorMsg.errorAt loc ("Duplicate pattern variable " ^ s)
adamc@329 212 | PatUnify (p, c1, c2, uerr) =>
adamc@329 213 (ErrorMsg.errorAt (#2 p) "Unification failure for pattern";
adamc@329 214 eprefaces' [("Pattern", p_pat env p),
adamc@329 215 ("Have con", p_con env c1),
adamc@329 216 ("Need con", p_con env c2)];
adamc@329 217 cunifyError env uerr)
adamc@329 218 | UnboundConstructor (loc, ms, s) =>
adamc@329 219 ErrorMsg.errorAt loc ("Unbound constructor " ^ String.concatWith "." (ms @ [s]) ^ " in pattern")
adamc@329 220 | PatHasArg loc =>
adamc@329 221 ErrorMsg.errorAt loc "Constructor expects no argument but is used with argument"
adamc@329 222 | PatHasNoArg loc =>
adamc@329 223 ErrorMsg.errorAt loc "Constructor expects argument but is used with no argument"
adamc@819 224 | Inexhaustive (loc, p) =>
adamc@819 225 (ErrorMsg.errorAt loc "Inexhaustive 'case'";
adamc@819 226 eprefaces' [("Missed case", p_pat env p)])
adamc@329 227 | DuplicatePatField (loc, s) =>
adamc@329 228 ErrorMsg.errorAt loc ("Duplicate record field " ^ s ^ " in pattern")
adamc@329 229 | OutOfContext (loc, co) =>
adamc@329 230 (ErrorMsg.errorAt loc "Type class wildcard occurs out of context";
adamc@329 231 Option.app (fn (e, c) => eprefaces' [("Function", p_exp env e),
adamc@329 232 ("Type", p_con env c)]) co)
adamc@329 233 | Unresolvable (loc, c) =>
adamc@329 234 (ErrorMsg.errorAt loc "Can't resolve type class instance";
adamc@850 235 eprefaces' [("Class constraint", p_con env c)(*,
adamc@711 236 ("Class database", p_list (fn (c, rules) =>
adamc@711 237 box [P.p_con env c,
adamc@711 238 PD.string ":",
adamc@711 239 space,
adamc@711 240 p_list (fn (c, e) =>
adamc@711 241 box [p_exp env e,
adamc@711 242 PD.string ":",
adamc@711 243 space,
adamc@711 244 P.p_con env c]) rules])
adamc@850 245 (E.listClasses env))*)])
adamc@329 246 | IllegalRec (x, e) =>
adamc@329 247 (ErrorMsg.errorAt (#2 e) "Illegal 'val rec' righthand side (must be a function abstraction)";
adamc@329 248 eprefaces' [("Variable", PD.string x),
adamc@329 249 ("Expression", p_exp env e)])
adamc@329 250
adamc@329 251
adamc@329 252 datatype decl_error =
adamc@329 253 KunifsRemain of decl list
adamc@329 254 | CunifsRemain of decl list
adamc@329 255 | Nonpositive of decl
adamc@329 256
adamc@329 257 fun lspan [] = ErrorMsg.dummySpan
adamc@329 258 | lspan ((_, loc) :: _) = loc
adamc@329 259
adamc@329 260 val p_decl = P.p_decl
adamc@329 261
adamc@329 262 fun declError env err =
adamc@329 263 case err of
adamc@329 264 KunifsRemain ds =>
adamc@329 265 (ErrorMsg.errorAt (lspan ds) "Some kind unification variables are undetermined in declaration";
adamc@329 266 eprefaces' [("Decl", p_list_sep PD.newline (p_decl env) ds)])
adamc@329 267 | CunifsRemain ds =>
adamc@329 268 (ErrorMsg.errorAt (lspan ds) "Some constructor unification variables are undetermined in declaration";
adamc@329 269 eprefaces' [("Decl", p_list_sep PD.newline (p_decl env) ds)])
adamc@329 270 | Nonpositive d =>
adamc@329 271 (ErrorMsg.errorAt (#2 d) "Non-strictly-positive datatype declaration (could allow non-termination)";
adamc@329 272 eprefaces' [("Decl", p_decl env d)])
adamc@329 273
adamc@329 274 datatype sgn_error =
adamc@329 275 UnboundSgn of ErrorMsg.span * string
adamc@1000 276 | UnmatchedSgi of ErrorMsg.span * sgn_item
adamc@1000 277 | SgiWrongKind of ErrorMsg.span * sgn_item * kind * sgn_item * kind * kunify_error
adamc@1000 278 | SgiWrongCon of ErrorMsg.span * sgn_item * con * sgn_item * con * cunify_error
adamc@1000 279 | SgiMismatchedDatatypes of ErrorMsg.span * sgn_item * sgn_item
adamc@1000 280 * (con * con * cunify_error) option
adamc@1000 281 | SgnWrongForm of ErrorMsg.span * sgn * sgn
adamc@329 282 | UnWhereable of sgn * string
adamc@329 283 | WhereWrongKind of kind * kind * kunify_error
adamc@329 284 | NotIncludable of sgn
adamc@329 285 | DuplicateCon of ErrorMsg.span * string
adamc@329 286 | DuplicateVal of ErrorMsg.span * string
adamc@329 287 | DuplicateSgn of ErrorMsg.span * string
adamc@329 288 | DuplicateStr of ErrorMsg.span * string
adamc@329 289 | NotConstraintsable of sgn
adamc@329 290
adamc@329 291 val p_sgn_item = P.p_sgn_item
adamc@329 292 val p_sgn = P.p_sgn
adamc@329 293
adamc@329 294 fun sgnError env err =
adamc@329 295 case err of
adamc@329 296 UnboundSgn (loc, s) =>
adamc@329 297 ErrorMsg.errorAt loc ("Unbound signature variable " ^ s)
adamc@1000 298 | UnmatchedSgi (loc, sgi) =>
adamc@329 299 (ErrorMsg.errorAt loc "Unmatched signature item";
adamc@329 300 eprefaces' [("Item", p_sgn_item env sgi)])
adamc@1000 301 | SgiWrongKind (loc, sgi1, k1, sgi2, k2, kerr) =>
adamc@1000 302 (ErrorMsg.errorAt loc "Kind unification failure in signature matching:";
adamc@329 303 eprefaces' [("Have", p_sgn_item env sgi1),
adamc@329 304 ("Need", p_sgn_item env sgi2),
adamc@623 305 ("Kind 1", p_kind env k1),
adamc@623 306 ("Kind 2", p_kind env k2)];
adamc@623 307 kunifyError env kerr)
adamc@1000 308 | SgiWrongCon (loc, sgi1, c1, sgi2, c2, cerr) =>
adamc@1000 309 (ErrorMsg.errorAt loc "Constructor unification failure in signature matching:";
adamc@329 310 eprefaces' [("Have", p_sgn_item env sgi1),
adamc@329 311 ("Need", p_sgn_item env sgi2),
adamc@329 312 ("Con 1", p_con env c1),
adamc@329 313 ("Con 2", p_con env c2)];
adamc@329 314 cunifyError env cerr)
adamc@1000 315 | SgiMismatchedDatatypes (loc, sgi1, sgi2, cerro) =>
adamc@1000 316 (ErrorMsg.errorAt loc "Mismatched 'datatype' specifications:";
adamc@329 317 eprefaces' [("Have", p_sgn_item env sgi1),
adamc@329 318 ("Need", p_sgn_item env sgi2)];
adamc@329 319 Option.app (fn (c1, c2, ue) =>
adamc@329 320 (eprefaces "Unification error"
adamc@329 321 [("Con 1", p_con env c1),
adamc@329 322 ("Con 2", p_con env c2)];
adamc@329 323 cunifyError env ue)) cerro)
adamc@1000 324 | SgnWrongForm (loc, sgn1, sgn2) =>
adamc@1000 325 (ErrorMsg.errorAt loc "Incompatible signatures:";
adamc@329 326 eprefaces' [("Sig 1", p_sgn env sgn1),
adamc@329 327 ("Sig 2", p_sgn env sgn2)])
adamc@329 328 | UnWhereable (sgn, x) =>
adamc@329 329 (ErrorMsg.errorAt (#2 sgn) "Unavailable field for 'where'";
adamc@329 330 eprefaces' [("Signature", p_sgn env sgn),
adamc@329 331 ("Field", PD.string x)])
adamc@329 332 | WhereWrongKind (k1, k2, kerr) =>
adamc@329 333 (ErrorMsg.errorAt (#2 k1) "Wrong kind for 'where'";
adamc@623 334 eprefaces' [("Have", p_kind env k1),
adamc@623 335 ("Need", p_kind env k2)];
adamc@623 336 kunifyError env kerr)
adamc@329 337 | NotIncludable sgn =>
adamc@329 338 (ErrorMsg.errorAt (#2 sgn) "Invalid signature to 'include'";
adamc@329 339 eprefaces' [("Signature", p_sgn env sgn)])
adamc@329 340 | DuplicateCon (loc, s) =>
adamc@329 341 ErrorMsg.errorAt loc ("Duplicate constructor " ^ s ^ " in signature")
adamc@329 342 | DuplicateVal (loc, s) =>
adamc@329 343 ErrorMsg.errorAt loc ("Duplicate value " ^ s ^ " in signature")
adamc@329 344 | DuplicateSgn (loc, s) =>
adamc@329 345 ErrorMsg.errorAt loc ("Duplicate signature " ^ s ^ " in signature")
adamc@329 346 | DuplicateStr (loc, s) =>
adamc@329 347 ErrorMsg.errorAt loc ("Duplicate structure " ^ s ^ " in signature")
adamc@329 348 | NotConstraintsable sgn =>
adamc@329 349 (ErrorMsg.errorAt (#2 sgn) "Invalid signature for 'open constraints'";
adamc@329 350 eprefaces' [("Signature", p_sgn env sgn)])
adamc@329 351
adamc@329 352 datatype str_error =
adamc@329 353 UnboundStr of ErrorMsg.span * string
adamc@329 354 | NotFunctor of sgn
adamc@329 355 | FunctorRebind of ErrorMsg.span
adamc@329 356 | UnOpenable of sgn
adamc@706 357 | NotType of ErrorMsg.span * kind * (kind * kind * kunify_error)
adamc@329 358 | DuplicateConstructor of string * ErrorMsg.span
adamc@329 359 | NotDatatype of ErrorMsg.span
adamc@329 360
adamc@329 361 fun strError env err =
adamc@329 362 case err of
adamc@329 363 UnboundStr (loc, s) =>
adamc@329 364 ErrorMsg.errorAt loc ("Unbound structure variable " ^ s)
adamc@329 365 | NotFunctor sgn =>
adamc@329 366 (ErrorMsg.errorAt (#2 sgn) "Application of non-functor";
adamc@329 367 eprefaces' [("Signature", p_sgn env sgn)])
adamc@329 368 | FunctorRebind loc =>
adamc@329 369 ErrorMsg.errorAt loc "Attempt to rebind functor"
adamc@329 370 | UnOpenable sgn =>
adamc@329 371 (ErrorMsg.errorAt (#2 sgn) "Un-openable structure";
adamc@329 372 eprefaces' [("Signature", p_sgn env sgn)])
adamc@706 373 | NotType (loc, k, (k1, k2, ue)) =>
adamc@706 374 (ErrorMsg.errorAt loc "'val' type kind is not 'Type'";
adamc@623 375 eprefaces' [("Kind", p_kind env k),
adamc@623 376 ("Subkind 1", p_kind env k1),
adamc@623 377 ("Subkind 2", p_kind env k2)];
adamc@623 378 kunifyError env ue)
adamc@329 379 | DuplicateConstructor (x, loc) =>
adamc@329 380 ErrorMsg.errorAt loc ("Duplicate datatype constructor " ^ x)
adamc@329 381 | NotDatatype loc =>
adamc@329 382 ErrorMsg.errorAt loc "Trying to import non-datatype as a datatype"
adamc@329 383
adamc@329 384 end